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From: "George Lendich" <lendich@optusnet.com.au>
To: "Rotary motors in aircraft" <flyrotary@lancaironline.net>
References: <list-1002462@logan.com>
Subject: Re: [FlyRotary] planetary gear ratios
Date: Wed, 15 Jun 2005 16:57:00 +1000
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Ernest,
If it turns counter clockwise it's the 2.17 ( you don't add the one in the
calculations).
If it turns clockwise it's 3.17.
The 2.17 turns counter clockwise.
The 2.85 turns clockwise ( looking at it from the pilots seat)
George ( down under)

> I ran across some information in one of the scientific newsgroups on how
> to calculate the gear ratio of a planetary gear set.
>
> ratio = 1 + r / s
>
> where: r = number of ring gear teeth
>            s = number of sun gear teeth.
>
> I haven't replace my 3-pinion gear set with a 6-pinion set, because I've
> not been able to positively identify it to where I could call out a part
> number.  Order strange gearset from the internet is not what I consider
> an efficient way to spend money.  So I went out and counted.  74 teeth
> on the ring and 34 on the sun.
>
> 1+74/34 = 3.176
>
> That is not the 2.17 OR the 2.85 from the Ford gear sets.  Is it
> possible that the one isn't added in standard practice, so that what I
> actually have is the 2.17 gear set?